Chronograph



ugs 27, E940.I L.. P, DORSETT ET AL pzz CHRONOGRAPH Filed Aug. l0, 1939 3 Sheets-Sheet l Allg. 27, 1 P. DORSETT ET AL CHRONOGRAPH Filed Aug. 10, 1939 3 Sheets-Sheet 2 Auge 27 T1949 L. P. BORSE-Vr m AL ZEQSE CHRONOGRAPH Filed Aug. 10, 1939 3 Sheets-Sheet 3 Invnnve, Lennard P Dmrfet Henschel ml-L Patented Aug. 27, 1--940 UNITED STATES PATENT OFFICE CHRONOGRAPH Leonard P. Dorsett, Bethlehem, and Herschel Smith, Southampton, Pa.

The invention described herein may be manuiactured and used by or for the Goverment for governmental purposes, without the payment to us of any royalty thereon.

This invention relates to improvements in chronographs and more particularly to electrically actuated chronographs adapted to measure and record time intervals of integral and very small fractional second values.

y@ Heretofore in the art it has been common practice in electrically actuated chronographs to employ sliding clutch plates, sliding shafts or similar movable members to connect the recording indicators with the clockwork train or similar l5 mechanism driven at known speed, and to use electromagnets for effecting engagement or disengagement of the movable members with the clockwork train. We have found, however, that movable members of the character above described are necessarily of such mass that their motions are retarded considerably through their inertias and that corresponding inaccuracies in the recording of the chronograph are in/troduced because of this time lag.

It is therefore, an object of this invention to provide an electrically actuated chronograph wherein moving parts operable in accordance with an electric signal or similar impulse have been altogether eliminated or so employed that J0 their masses may be much less than required in the movable members above referred to.

It is a further object of the invention to provide electromagnets for directly and positively initiating and effecting cessation of movement of the recording indicators by the clockwork train or similar mechanism driven at known speed, concurrently and respectively with suitable signals indicating the beginning and termination of the interval of time to be measured.

It is still a further object of the invention to provide a suitable thermionic relay for controlling the action of the electromagnets in proper sequence and with minimum time lag.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

Fig. 1 is a side elevation partially in section of a chronograph constructed in accordance with the invention;

Fig. 2 is a fragmentary elevation of a part of the structure shown in Fig.'1;

Fig. 3 illustrates schematically one embodiment of a thermionic relay circuit adapted to electromagnet suitable for use in the chronograph;

Fig. 6 is a sectional view taken on the line 6 6 of Fig. 7 of still another modication of an elec- 10 tromagnet that may be used in lieu of the ones shown in Fig. 1 or 5;

Fig. '7 is an elevation oi the structure shown in Fig. 6 looking in the direction of arrow A.

Fig. 8 illustrates an alternate method of driv- 15 ing the rotatable pole piece and securing the electromagnet to the frame;

Fig. 9 illustrates an alternate method of arranging the movable armatures;

Fig. 101s a perspective View of the chronograph 20 with parts broken away and other parts omitted to clearly show the zeroizing and switch mechanisms.

Referring now to the drawings by characters of reference there is shown in Fig. 1 a chrcno- 25 graph mounted in a supporting frame comprising a front plate lll and rear plate II joined to each other in spaced parallel relation by spacers I2 of any suitable design. An annular electromagnet I3 is secured to the rear plate ll of the 30 frame in spaced substantial parallel relation therewith by means of spacers I 4 and is provided with a rotatable pole piece I5 secured to an annular-core I6 journaled on a stub shaft Il of non-magnetic substance. The shaft l'l may con- 35 veniently be secured at one end to the rear plate il in iixed relation by any desirable seeming means, such as shown at i8, and flanged, 'upset or otherwise formed at its opposite end I8' to retain the core d6 in proper bearing relation 40 thereon. Another annular electromagnet indicated at I9 and provided with a stationary pole piece 20 and annular core 2l is secured in spaced substantial parallel relation to the front plate I0 by spacers 22. A rotatable shaft 23 is jour- 45 naled at its rear end Within a suitable bore in the stub shaft I1 and intermediate its ends in the front plate I 0. The shaft 23 extends through the annular core 2| of electromagnet I9 and has aflixed to its front end an indicator 24. Interme- 50 diate the electromagnets I3 and I9 the shaft has affixed thereon for rotatable movement therewith armatures 25 and 26 adapted to cooperate respectively with the pole pieces I5 and 20. Each armature is comprised of substantially identical 55 ture member 28. It will be observed that in this manner of attachment of the armatures that they may move in directions parallel with the axis of the shaftl 23 independent of the shaft and v that the only inertia to be overcome in effecting their movement is due to the relative slight masses of the armature constructions. The rotatable core I6 secured to the pole piece I5 projects to the rear of the electromagnet I3 and carries a gear 29 rigidly thereon and constituting one of the gears of a gear train 30 of any desired driving ratio'driven by a small synchronous motor 3|. Conductors 32 and 33 connect the motor 3| with any convenient source of alternating current. At its forward end the shaft 23 has sleeved thereover a. sleeve 33 carrying a second indicator 35 whichis driven through the sleeve and a suitable gear train 36 driven by shaft 23 so as to be driven at` a preselected ratio with respect to the shaft 23 and indicator 24. A dial 31 graduated in any appropriate units of time interval is suitably positioned in rear of the indicators 24 and 35 from which a measured time interval may be directly read as indicated by the indicators.

When the chronograph has functioned to measure and record an interval of time it is of course necessary that the indicators 24 and 35 be reset to zero or zeroized before the chronograph is in condition for subsequent measurement by direct reading and for this purpose the resetting or zeroizing device more particularly shown in Figs. l and 2 is provided which comprises a rotatable shaft 38, having at its forward end a crankedarm 39, mounted in the frame plates I0 and II for rotation. A shaft 40 similar to shaft 38 is mounted in the frame plates I8 and II for rotation on an axis parallel with and contained in substantially the same horizontal plane as the latter. The axis of shaft 4I) is also substantially parallel with the axis of shaft 23 and is disposed to one side of the vertical plane containing the axis of shaft 23 a suitable distance as shown in Fig. 2. At its upper end a depending lever 4I is frictionally or otherwise suitably secured to the shaft 38 and is provided at its lower end with a perforated spring abutment 42. The lever 4I is normally held in engagement with a stop 43 on the frame plate |Il by resilient means 44 initially tensioned so as to bias the lever in a counterclockwise direction away from shaft 23 as viewed in Fig. 2. Shaft 40 is provided with two longitudinally spaced depending levers as indicated at 45. and 46 respectively, in both Figs.

1 and 2. The lever 45depends to a position in substantial horizontal alignment with the lower end of lever `4I and is provided with a perforated spring abutment 41 which cooperates with the K abutment 42 on lever 4| to support a compression spring 48 interposed between the two abutments and held under initial compression by a telescopic member 49 extended through the perforations of opposed abutments. The telescopic member is of -such length in extended position and so secured to the abutments as to normally rewith heart shaped cams 5I and 5I mounted respectively on the shaft 23 and sleeve 34. As will be seen hereinafter depression of arm 39 will rotate shaft 38 and lever 4| in a lclockwise direction as viewed in Fig. 2 and such rotation will be imparted to lever 45 through the spring 48 and to lever 46 through the shaft 48 to cause the rollers 50 to engage the heart shaped cams 5I' and 5I and rotate the shaft 23 and sleeve 34 to a position where the indicators 24 and 35 indicate zero on the graduated dail 31.

In order to control the thermionic circuit hereinafter described during the zeroizing of the indicators 24 and 35 a switch box housing switches SP and SG is mounted for convenience on the frame plate II and actuators of non-conducting material, indicated respectively at AP and AG are mounted on the shaft 38 and so arranged as to open the switches SP and SG in proper sequence upon rotation of the shaft 38 in clockwise direction as viewed in Fig. 2.

A relay circuit of the thermionic type suitable for effecting energization and deenergization of the electromagnet coils I3 and I9 in proper sequence in measuring a time interval is shown schematically in Fig. 3. As shown means 52, which may be a transformer with its primary connected in the starting signal circuit is arranged to be generally affected by any suitable signal initiating the interval of time to be measured and 53 is similar means arranged to be operably affected by any suitable signal indicating the termination of the time interval measured. A pair of gaseous triodes TI and T2 having input' and output circuits are arranged to have` their outputs regulated by thev means 52 and 53 through the input circuits. The cathodes of the triodes are heated by any suitable source of power` such as 54 and include in common in their input circuits any suitable grid biasing source 55. Ihe input circuit of triode T2 comprises the grid resistor r2 leak resistor r4 and secondary of the transformer included in means 52 and likewise the input circuit of triode 'II comprises the grid resistor rI leak resistor r3 secondary of the transformer of means 53 and in addition the switch SG hereinbefore mentioned. 'Ihe output circuit of both triodes include in common the anode current source 56. The output circuit of triode T2 comprises the electromagnet I3 and onehalf of the resistance R and the output circuit of triode 'I'I includes the electromagnet I9, onehalf the resistance R and switch SP hereinbefore referred to. The condenser 51 is disposed in parallel with the electromagnets as shown.

The operation ofthe system thus far described isas follows:

During the zeroizing operation of the indicators 24 and 35 to be hereinafter more fully set forth, the switch SG is momentarily opened which changes the grid bias on triode TI to such an extent that the triode becomes conducting and initiates iiow of current in the plate circuit through the electromagnet I9. 'I'he electromagnet I9 upon being energized by ow of current in the plate circuit of triode TI attracts armature 26 to stationary pole piece 20 and restrains shaft 23 against movement thereby holding indicators 24 and 35 in the zero position. Flow of current in the plate circuit of triode TI induces a charge on condenser 51 because of the potential drop across the resistance of electromagnet I9 and one-half of resistance R.. The system is now conditioned to measure an interval of time and upon the impression of an electric signal indicating the commencement of the time interval to be measured on the primary of thetransformer included in means 52 an E. M., F. will be induced in the secondary of the transformer and so modify the grid bias of the input circuit of triode T2 that this triode will become conducting and a plate current will flow in the output circuit. Flow of current in the output circuit of triode T2 will energize the electromagnet I3 attracting the armature 25 to the pole piece I5. Simultaneously with ilow of current in the output circuit of triode T2 the condenser 51 discharges through triode 'I2 because of the change in potential of this plate circuit with respect to the plate circuit of triode 'I'I and the plate of triode 'II becomes momentarily more negative than its cathode thereby causing the current ow in the output circuit of triode TI to cease with accompanying deenergization of electromagnet I9 and retraction of the armature 26 by springs 2l to release shaft 23 for rotation. The pole piece I is rotated by the synchronous motor 3| energized from a suitable A. C. source through conductors 32 and 33 and it will of course be understood that motor 3l has been brought to synchronous speed prior to the impression of a starting signal on means 52. The indicators 24 and 35 are driven by the motor 3| through the train gear 30, rotating pole piece I5, armature 25, shaft 23, and gear train 36 at known speed until the expiration of the time interval whereupon a signal is impressed on means 53 to induce an E. M. F. in the secondary of the transformer of this means and modify the bias on the triode TI grid so as to start flow of currentl in the plate circuit of this triode. When current again flows in the output circuit of the triode TI the condenser 5l, which was charged when electromagnet I9 was deenergized as above described in a sense opposite to that in which it was charged prior to discharging through triode T2 will discharge through triode TI rendering triode T2 non-conducting with accompanying deenergization of electromagnet I3 and release of shaft 23 from driven relation with therotating pole piece I5 and electromagnet I9 will be energized attracting armature 26 and stopping rotation of shaft 23. The time interval measured may now be read directly from the dial 3l as indicated by the indicators 24 and 35.

When the measured time interval has been read from the dial 3'I the indicators are reset to' zero to condition the system for subsequent operation by' direct reading and this is done through the zeroizing mechanism. It is of course obvi ous that when current is flowing in the plate of triode TI that the shaft 23 will resist rotation since armature 26 is strongly attracted by electromagnet I9 and therefore the indicators cannot be set to zero without rst deenergizing electromagnet I9. This is done when resetting crank 39 is depressed to rotate shaft 38 which causes the actuator AP on the shaft 38 to open the switch SP during initial movement of the shaft and thereby break the plate circuit of triode TI to deenergize the electromagnet I9` Further rotation of shaft 38 will close the switch SP which conditions triode 'I'I to conduct when the bias on its grid is suitably changed. Deenergization of electromagnet I9 will permit the indicators 24 and 35 to be returned to zero, therefore continued depression of resetting crank 39 and rotation of shaft 39 will cause the lever 4I through the spring connection 48 to rotate the levers- 45 and 49 so asto bring the rollers 50 into engagement with the cams 5I and 5I to rotate the 'same to position the indicators to zero in a manner well understood in the art. When the indicators have been returned to zero the rollers 50 will engage in the depressions of the heart shaped cams 5I and 5I and further rotation of shaft 38 will cause spring 48 to compress so that lever 4I will move relative to the levers 45 and 46 and this additional rotation of shaft 33 will cause the actuator AG' to open switch SG in the grid circuit of triode TI and so change the grid bias on this triode that it will become conducting as above set forth and energize the plate circuit and electromagnet I9 so that the indicators will be held in 'the zero position. Upon release of the reset crank 39 the spring 44 returns the levers 4I, 45 and 46 to their initial positions without opening switch SP and closing switchA SG and the system is again in condition for operation as above described.

In Fig. 4 a modified form of thermionic relay circuit is shown suitable for use in the chronograph system which eliminates the necessity of employing a zeroizing mechanism such as shown in Figs. 1 and 2. In this form of relay a pair of gaseous triodes TI and T2 of the separate heater type are shown. The cathodes of the triodes are heated through any suitable source of power such as 63. The input circuit of triode T2 comprises the starting signal means including resistance f5, the resistances r6 and rl, condenser 6I, and biasing source 62. 'I'he input circuit of triode 'II comprises the stopping signal means including resistance T8, the resistances r9 and TIO, condenser 63 and biasing source 62. The condenser 64 is connected to the cathodes of the triodes in parallel with resistances r'l and TIO. The output circuits of the triodes include a common source of power for the anodes of the triodes T2 and TI and the electromagnets I3 and I9, respectively. Condensers 65 and 66 are placed in parallel with the electromagnets I3 and I9, respectively, and are chosen to have a minimum time constant in switching the current in the output circuits of the triodes from one electromagnet to the other.

A depressible reset switch 6l is arranged in the plate circuits of both triodes and in the grid circuit of triode TI so that upon initial depression of the switch the grid of vtriode TI will be grounded through resistance rII and thereafter upon further depression will open the plate supply circuit.

The operation of the thermionic relay shown in Fig. 4 in the chronograph system is as follows:

Thev reset switch 61 is depressed which first grounds the grid of triode TI and then opens the plate circuits of both triodes TI and T2 to deenergize the electromagnets I3 and I9 which then permit zeroizing of the indicators 24 and 35 through the use of the levers 4I, 45, 46 and heart shaped cams 5I' and 5I as hereinbefore described or in any other suitable manner. 4

Upon release of the reset switch the plate circuits of the triodes are closed before the grid of triode TI is ungrounded and this renders triode TI conducting and effects a current flow through the output circuit thereof to energize electromagnet I9 and attract armature 26, which prevents shaft 23 from rotating with consequent displacement of the indicators from zero? position.

After the plate circuits are closed further release of the reset switch from its depressed position ungrounds the grid of triode TI and condenser 64 is charged by the drop in potential across retransmitted across condenser 6I raising the po` tential of the grid in triode T2 to the extent that the triode becomes conducting. Current will then iiow through the output circuit of this triode and energize electromagnet I3 thereby attracting the armature 25 attached to shaft 23 to the pole piece I5 being rotated by the synchronous motor 3| and displace the indicators 24 and 35 accordingly. Simultaneously with initiation of current iiow in the output circuit of triode T2 condenser 64 will discharge through triode T2 momentarily raising the cathode potential of triode TI above the plate potential to render the triode non-conducting. Current then ceases to flow in triode TI and electromagnet I9 is deenergized to release the armature 26 and permit rotation of shaft 23. Upon expiration of the time interval being measured-an electric signal will be momentarily applied across the resistance 18 of the stopping means across the condenser 63 to the grid of the triode TI so raising its potential that the triode becomes conducting and current is thereby switched from electromagnet I3 to electromagnet I9 to release armature 25 from the rotating pole piece I5 and stop the shaft 23 by attraction of armature 26 to the fixed pole piece 20 all in a manner similar to the one in which the starting signal aiects the circuits of the triodes as above explained. The interval of time measured may now be directly read from the dial 31 indicated by the indicators 25 and 35 and the system conditioned for subsequent operation as above.

In Fig. 5 a modified form of electromagnet I 3' is shown which may be used in lieu of the electromagnet I3. In this form the coil housing of annular electromagnet I3', pole piece I5' and annular core I6' are all secured together and mounted on a stud shaft I1 for rotation as a unit. The housing of the electromagnet carries the spaced annular contacts 68 insulated from each other by the insulating medium 63 and suitably connected with the terminals of the coil of the electromagnet. Brushes 10 properly connected in the output circuit of triode TI serve to conduct an energizing current to the annular contacts 58. This electromagnet functions in the system in the same manner as electromagnet I3, being driven by the gear 29 through the gear train 30 and synchronous motor 3l.

In Figs. 6 and 7 a further modification of the electromagnet I3 is shown at I3" but this modification may with equal facility be applied to the stationary pole piece 20 of the electromagnet I9. In this modification the pole piece I5" comprises an annular soft iron, or similar substance of high magnetic permeability, piece 1I of smaller diameter than the electromagnet coil housing, an annular piece 12 of material of non-magnetic substance, such as brass and another annular member 13 having an outside diameter substantially equal to the coil housing of the same substance as piece 1I secured to piece 12. The pole piece I5" is secured to an annular core I6" mounted for rotation on the stud shaft I1" and adapted to be rotated by the gear 29". The pole piece I5" and core I6" are spaced by very small air gaps 14 from the coil to permit rotation thereof and reduce the reluctance of the magnetic path to a. minimum. In effect the non-magnetic ring 12 separates the pole piece I5" into two poles thus concentrating the magnetic force through the cooperating armatures 2 5 and making them cling to the pole face more securely.` The gap with pole piece I5" caused by 12 may be made relatively wide. For economy in organization it may be desirable to secure the gear 29" directly to the periphery of annular member 13 in the form of a ring gear whereby housing I3 may be fastened directly to the frame plate II as shown in Fig. 8'.

As disclosed in Fig. 9 each armature assembly may consist of a light weight disc 15 secured to the shaft 23 at a predetermined distance from the cooperating pole piece and in substantially parallel relation therewith. A plurality of armature members 16 of any convenient shape and each having a polygonal shaped boss 11 projecting through a correspondingly shaped aperture in the disc are disposed around the disc and urged into contact therewtih by springs 18 interposed between the disc and suitable abutments 19 on the bosses. This arrangement allows the light armature members 16 to move freely parallel to the axis of the shaft 23 between the two positions, against the pole piece and at a xed distance from it against the disc. The bosses passing through the holes in the disc prevent any relative rotat-able motion between the armature members and the disc.

Having now described our invention what we claim is:

1. In a chronograph system in combination, a rotatable shaft, an indicator having a normal zero position driven'by said shaft,'an electromagnet mounted adjacent the shaft, an armature exibly secured to the shaft and adapted to be coupled with the electromagnet to restrain the shaft against rotation with the indicator in its normal zero position through energization o-f the electromagnet, a second electromagnet having a rotatable pole piece mounted adjacent the shaft, and a second armature em'bly secured to the shaft and adapted to be coupled with the roy tatable pole piece through energization of the second electromagnet.

2. In a chronograph system in combination, a supporting frame comprising front and rear spaced plates, an electromagnet having a stationary annular core and attached pole piece secured to the front plate with the axis of its core intersecting the front plate, a second electromagnet having a rotatable annular core and attached pole piece secured to the rear plate with the axis of its core in alignment with said first recited axis, means-mounting the rotatable annular core for rotation, a rotatable shaft journaled in said last recited means and front plate extending through the core of the first recited electr'omagnet, a pair of substantially identical armatures exibly secured to the rotatable shaft intermediate the electromagnets and adapted to be coupled with the pole pieces of the iirst and second recited electromagnets respectively through energization of the latter.

' 3. In a chronograph system in combination, a rotatable shaft, an indicator driven by the shaft, a rst electromagnet having a stationary pole piece adapted to restrain the shaft against rotation, means for driving the shaft comprising a second electromagnet having a 'rotatable pole piece adapted to be coupled with the shaft, starting signal means, an electronic device having an input circuit coupled with the starting signal means and an output circuit including said second electromagnet, stopping signal means, an electronic device having an input circuit coupled with the stopping signal means and an output circuit including said first electromagnet, a condenser connected across said output circuits operable to render the output circuit of the electronic device coupled with the stopping signal means non-conducting when the output circuit of the other electronic device is conducting and viceversa and means for resetting the indicator to zero position when current is flowing in the output circuit of the electronic device including the rst electromagnet, comprising means toopen and close the output circuit in sequence to stop flow of current in the output circuit, means to reset the indicator to zero position and means to initiate flow of current in the output circuit including a device operable to open and close the input circuit of said electronic device in sequence.

4. In a chronograph system, a supporting frame comprising front and rear plates, a rotatable shaft mounted in said frame, an indicator secured to the shaft, a sleeve mounted on the shaft and rotatable relative thereto, a second indicator secured to the sleeve, heart shaped cams secured to the shaft and sleeve respectively, a rotatable shaft mounted on the front and rear plates in parallel relation wtih said rst recited rotatable shaft, levers secured to said rotatable shaft mounted in the front and rear plates and depending to a position adjacent the heart shaped cams, rollers mounted on the levers and adapted to engage the cams, an actuator lever shaft mounted in the front and rear plates in parallel relation wtih said other rotatable shafts, an actuator lever secured to said actuator lever shaft and resiliently connected at its lower end with one of said rst recited levers, means restraining the interconnected levers against relative movement in one direction, means biasing said levers to a normal position in the direction of restrained relative movement with the rollers out of engagement With the heart shaped cams, means for rotating the levers contra to the biasing means, electromagnetic means for restraining said first recited shaft against rotation, an electronic device having input and output circuits for controlling energization of the electromagnet means, switches in the input and output circuits, and switch actuators secured to said actuator lever shaft ln cooperating relation with the switches and adapted to open and close said switches in sequence.

LEONARD P. DORSE'I'I. HERSCI-IEL SMITH. 

